title: Vitamin D deficiency, interleukin 17, and vascular function in rheumatoid arthritis.
abstract: OBJECTIVE
  Vitamin D deficiency is associated with increased cardiovascular (CV) disease risk in the general population. We examined the association between vitamin D deficiency and CV risk in rheumatoid arthritis (RA).
  
  
  METHODS
  We measured large artery compliance by pulse wave velocity and microvascular function by the reactive hyperemia index in patients with stable RA (n = 87). We quantified CV risk factors, serum 25-hydroxyvitamin D [25(OH)D], and interleukin 17 (IL-17), and RA disease activity by Disease Activity Score of 28 joints. We used linear regression to test associations between serum 25(OH)D and CV risk factors.
  
  
  RESULTS
  The mean serum 25(OH)D level in the cohort was 27.1 ± SD 13.6 ng/ml. Fifty-nine patients (68%) were vitamin D-insufficient (25(OH)D < 30 ng/ml; mean 20.2 ± 5.9 ng/ml) and of these, 25 (29%) were vitamin D-deficient (25(OH)D < 20 ng/ml; mean 14.4 ± 3.4 ng/ml). In the whole cohort and the vitamin D-insufficient group, serum 25(OH)D was inversely associated with IL-17 (log IL-17; β = -0.83, p = 0.04; β = -0.63, p = 0.004, respectively) by univariate analysis, which persisted after adjustment for season, and in multivariate analysis after adjustment for confounders (log IL-17; β = -0.74, p = 0.04; β = -0.53, p = 0.02). In vitamin D-deficient patients, serum 25(OH)D was positively associated with microvascular function by univariate and multivariate analysis after adjustment for confounders (β = 2.1, p = 0.04; β = 2.7, p = 0.04).
  
  
  CONCLUSIONS
  Vitamin D deficiency in RA may affect Th17 responses and microvascular function. Maintaining normal serum vitamin D levels may protect against IL-17-mediated inflammation and vascular dysfunction in RA.
authors.affiliation: Division of Rheumatology, Washington University School of Medicine, St. Louis, Missouri 63110, USA. prangana@dom.wustl.edu
authors.forename: Prabha
authors.initials: P
authors.lastname: Ranganathan
authors.forename: Shokoufeh
authors.initials: S
authors.lastname: Khalatbari
authors.forename: Srilakshmi
authors.initials: S
authors.lastname: Yalavarthi
authors.forename: Wendy
authors.initials: W
authors.lastname: Marder
authors.forename: Robert
authors.initials: R
authors.lastname: Brook
authors.forename: Mariana J
authors.initials: MJ
authors.lastname: Kaplan
mesh_terms: D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000097:blood* / Q000150:complications; D002318:Cardiovascular Diseases / Q000097:blood / Q000209:etiology*; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D020381:Interleukin-17 / Q000097:blood*; D008297:Male; D008875:Middle Aged; D063177:Pulse Wave Analysis; D012307:Risk Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood* / Q000150:complications
chemical_list: D020381:Interleukin-17; D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: INTERLEUKIN 17; MICROVASCULAR FUNCTION; RHEUMATOID ARTHRITIS; VITAMIN D